Cook the pasta to al dente in well-salted water, according to package instructions. Drain, but do not rinse the pasta.
In a blender, combine the roasted garlic, cashews, milk, nutritional yeast and miso if using, lemon zest, and lemon juice, until completely smooth. Add salt and pepper to taste.
In a medium-sized saucepan, warm the olive oil, and saute the shallot until softened. Add the cashew mixture, and cook over medium-low heat, stirring frequently, until warm throughout. Fold in the cooked pasta, and cook together over low heat just until warm and the sauce coats the pasta. Add more lemon juice, salt, and pepper to taste, and serve hot, garnished with fresh herbs if desired.